The present invention is directed to an improved process for the preparation of side chain derivatives of certain amine-containing cyclohexapeptidyl lipopeptides. These side chains are attached at the .alpha.-amino-nitrogen of the 1-[hydroxyornithine] residue of the cyclohexapeptide which can be represented by the formula (SEQ ID NO. 1) ##STR2## wherein R.sup.1 is hereinafter fully defined.
Previously, side chain derivatives of these amine-containing lipopeptides have been prepared via a deacylation-reacylation sequence followed by the chemical conversion of the 3-hydroxyglutamine residue to a 3-hydroxyomithine residue. This scheme, however, provides very low yields and requires optimization for each derivative.
It is therefore an object of this invention to provide an improved process for the preparation of the side chain derivatives in high yield.